Process for the obtainment of a polyolefin composition

ABSTRACT

A two steps polymerization process for obtaining a polyolefin composition comprising:
     a) from 25 wt % to 70 wt % of a propylene homopolymer or a propylene-ethylene copolymer containing from 0.1 wt % to 10 wt % of ethylene derived units;   b) from 27 wt % to 70 wt % of a copolymer of ethylene and at least one C 3 -C 20  alpha olefins, wherein the ethylene derived units content ranges from 15 wt % to 70 wt %;   c) from 3 wt % to 20 wt % of polyethylene homopolymer or an ethylene and at least one C 3 -C 20  alpha olefins copolymer;   the sum a)+b)+c) being 100,   wherein said process comprises:   step a) contacting under polymerization conditions propylene, optionally ethylene and the catalyst system in order to obtain component a),   step b) contacting under polymerization conditions ethylene and at least one C3-C20 alpha-olefins and the catalyst system in order to obtain components b) and c);   wherein the catalyst system comprises a metallocene compound and an iron complex.

This application is the U.S. National Phase of PCT InternationalApplication PCT/EP2013/062686, filed Jun. 19, 2013, claiming benefit ofpriority to European Patent Application No. 12172508.9, filed Jun. 19,2012, and benefit of priority under 35 U.S.C. §119(e) of U.S.Provisional Application No. 61/662,286 filed Jun. 20, 2012, the contentsof which are incorporated herein by reference in their entirety.

FIELD OF THE INVENTION

The present invention relates to a polymerization process for theobtainment of a polyolefin based composition comprising an heterophasicpropylene based polymer and polyethylene.

BACKGROUND OF THE INVENTION

Polyolefin compositions comprising an heterophasic propylene polymer andpolyethylene are well known in the art. For example WO 2006/067023relates to a polypropylene composition comprising (per cent by weight):

-   -   a) 50-77% of a crystalline propylene polymer;    -   b) 13-28% of an elastomeric copolymer of ethylene and propylene;        and    -   c) 10-22% of polyethylene.

WO 2006/125720 relates to a propylene polymer composition comprising(per cent by weight):

a) 65-77% of a crystalline propylene polymer,

b) 8 to less than 13% of an elastomeric copolymer of ethylene andpropylene; and

c) 10-23% of polyethylene.

These composition are obtained by using Ziegler Natta catalyst with athree steps process, one for each component of the composition.

Even metallocene based catalyst systems have been used for theobtainment of such three components compositions, for example in EP 646624 examples 21 and 22 this kind of composition is exemplified, howeverthere is always the need of a three steps process or to blend the threecomponents in order to obtain the composition.

SUMMARY OF THE INVENTION

The applicant found that a composition comprising a polypropylene matrixan ethylene rubber and polyethylene can be advantageously obtained witha two steps process by using a particular catalyst system.

DETAILED DESCRIPTION OF THE INVENTION

Thus an object of the present invention is a two steps polymerizationprocess for obtaining a polyolefin composition comprising:

-   a) from 25 wt % to 70 wt % of a propylene homopolymer or a    propylene-ethylene copolymer containing from 0.1 wt % to 10 wt %;    preferably from 0.1 wt % to 5 wt % of ethylene derived units;-   b) from 27 wt % to 70 wt % of a copolymer of ethylene and at least    one C₃-C₂₀ alpha olefins, wherein the ethylene derived units content    ranges from 15 wt % to 70 wt %;-   c) from 3 wt % to 20 wt % of polyethylene homopolymer or an ethylene    and at least one C₃-C₂₀ alpha olefins copolymer containing from 99.9    wt % to 95.0 wt % of ethylene derived units,-   wherein the at least one C₃-C₂₀ alpha olefins comonomer is the same    used in component b); the sum a)+b)+c) being 100    wherein said process comprises:-   step a) contacting under polymerization conditions propylene,    optionally ethylene and the catalyst system in order to obtain    component a)-   step b) contacting under polymerization conditions ethylene and at    least one C₃-C₂₀ alpha olefins and the catalyst system in order to    obtain components b) and c);    wherein the catalyst system comprises:-   i) a metallocene compound of formula (I)

Wherein

-   M is titanium zirconium or hafnium;-   X, same or different, is a hydrogen atom, a halogen atom, or a R,    OR, OSO₂CF₃, OCOR, SR, NR₂ or PR₂ group, wherein R is a linear or    branched, cyclic or acyclic, C₁-C₄₀-alkyl, C₂-C₄₀ alkenyl, C₂-C₄₀    alkynyl, C₆-C₄₀-aryl, C₇-C₄₀-alkylaryl or C₇-C₄₀-arylalkyl radicals;    optionally containing heteroatoms belonging to groups 13-17 of the    Periodic Table of the Elements; preferably R is a linear or branched    C₁-C₂₀-alkyl radical; or two X can optionally form a substituted or    unsubstituted butadienyl radical or a OR′O group wherein R′ is a    divalent radical selected from C₁-C₄₀ alkylidene, C₆-C₄₀ arylidene,    C₇-C₄₀ alkylarylidene and C₇-C₄₀ arylalkylidene radicals; preferably    X is fluorine, chlorine, bromine, iodine or a C1-C10-alkyl radical    such as methyl, ethyl, propyl or butyl radical;-   R¹, R², R³, R⁴, R⁵, R⁶ and R⁷, equal to or different from each    other, are hydrogen atoms or C₁-C₄₀ hydrocarbon radicals optionally    containing heteroatoms belonging to groups 13-17 of the Periodic    Table of the Elements; or two or more groups between R¹, R², R³, R⁴,    R⁵ and R⁶ can be fused to form a saturated or unsaturated, 5 or 6    membered rings, said ring can bear C₁-C₂₀ alkyl radicals as    substituents; preferably R¹, R², R³, R⁴, R⁵ and R⁶ are hydrogen    atoms or C₁-C₂₀-alkyl, C₂-C₂₀-alkenyl, C₆-C₂₀-aryl,    C₇-C₄₀-alkylaryl, C₇-C₄₀-arylalkyl radicals optionally containing    heteroatoms belonging to groups 13-17 of the Periodic Table of the    Elements; or two or more groups between R¹, R², R³, R⁴, R⁵ and R⁶    can be fused to form a saturated or unsaturated, 5 or 6 membered    rings, said ring can bear C₁-C₂₀ alkyl radicals as substituents;-   ii) at least one iron complex of the general formula (II)

Wherein:

-   the radicals X¹, equal to or different from each other, are hydrogen    atoms, halogen atoms, R, OR, OSO₂CF₃, OCOR, SR, NR₂ or PR₂ groups,    wherein R is a linear or branched, saturated or unsaturated C₁-C₂₀    alkyl, C₃-C₂₀ cycloalkyl, C₆-C₂₀ aryl, C₇-C₂₀ alkylaryl or C₇-C₂₀    arylalkyl radical, optionally containing heteroatoms belonging to    groups 13-17 of the Periodic Table of the Elements; or two X¹ can    optionally form a substituted or unsubstituted butadienyl radical or    a OR′O group wherein R′ is a divalent radical selected from C₁-C₂₀    alkylidene, C₆-C₄₀ arylidene, C₇-C₄₀ alkylarylidene and C₇-C₄₀    arylalkylidene radicals; preferably X¹ is a hydrogen atom, a halogen    atom or a R group; more preferably X is chlorine or a methyl    radical;-   D is an uncharged donor; s is 1, 2, 3 or 4, preferably s is 2 or 3;    t ranges from 0 to 4, preferably t is 0, 1 or 2.-   R⁸, equal to or different from each other, are hydrogen atoms or    C₁-C₄₀ hydrocarbon radicals optionally containing heteroatoms    belonging to groups 13-17 of the Periodic Table of the Elements;    preferably R⁸ are hydrogen atoms or linear or branched, cyclic or    acyclic, C₁-C₄₀-alkyl, C₂-C₄₀ alkenyl, C₂-C₄₀ alkynyl, C₆-C₄₀-aryl,    C₇-C₄₀-alkylaryl or C₇-C₄₀-arylalkyl radicals optionally containing    heteroatoms belonging to groups 13-17 of the Periodic Table of the    Elements; more preferably R⁸ are hydrogen atoms or C₁-C₁₀-alkyl    radicals;-   R¹⁰, equal to or different from each other, are hydrogen atoms or    C₁-C₄₀ hydrocarbon radicals optionally containing heteroatoms    belonging to groups 13-17 of the Periodic Table of the Elements;    preferably R¹⁰ are hydrogen atoms or linear or branched, cyclic or    acyclic, C₁-C₄₀-alkyl, C₂-C₄₀ alkenyl, C₂-C₄₀ alkynyl, C₆-C₄₀-aryl,    C₇-C₄₀-alkylaryl or C₇-C₄₀-arylalkyl radicals optionally containing    heteroatoms belonging to groups 13-17 of the Periodic Table of the    Elements; more preferably R¹⁰ are C₁-C₁₀-alkyl radicals such as    methyl or isopropyl radicals;-   R⁹, equal to or different from each other, are hydrogen atoms,    halogen atoms, preferably chlorine, or C₁-C₄₀ hydrocarbon radicals    optionally containing heteroatoms belonging to groups 13-17 of the    Periodic Table of the Elements; preferably R⁹ are hydrogen atoms    halogen atoms or linear or branched, cyclic or acyclic,    C₁-C₄₀-alkyl, C₂-C₄₀ alkenyl, C₂-C₄₀ alkynyl, C₆-C₄₀-aryl,    C₇-C₄₀-alkylaryl or C₇-C₄₀-arylalkyl radicals optionally containing    heteroatoms belonging to groups 13-17 of the Periodic Table of the    Elements; more preferably R⁹ are C₁-C₁₀-alkyl radicals such as    methyl or ethyl or halogen atoms, preferably chlorine;

iii) an alumoxane or a compound capable of forming an alkyl cation withcomplexes of formula (I) and (II);

The ratio between the compound of formula I) and II) depends from thewished product to be obtained. As a general rule the molar ratio betweenthe metallocene compound of formula (I) and the iron complex of formula(II) (M/Fe ratio) ranges from 1:1 to 50:1; preferably from 2:1 to 10:1;more preferably from 3:1 to 10:1.

Preferably the metallocene compound of formula (I) is in the racemic(rac) or racemic-like form. The terms racemic or racemic-like aredefined in WO03/046022.

Preferably the compound of formula (I) has formula (Ia)

Wherein

-   M, X, R¹, R², R⁴, R⁵, R⁶ and R⁷, have been described above; R^(1a)    is a moiety of formula (III)

Wherein

The symbol * marks the bound with the cyclopentadienyl moiety; R¹³,equal to or different from each other, is a C₁-C₁₅ hydrocarbon radicaloptionally containing heteroatoms belonging to groups 13-17 of thePeriodic Table of the Elements; preferably R¹³ is a C₁-C₁₀ alkylradical.

-   R¹⁴ is a hydrogen atom or a C₁-C₁₅ hydrocarbon radical optionally    containing heteroatoms belonging to groups 13-17 of the Periodic    Table of the Elements; preferably R¹⁴ is a hydrogen atoms or a    C₁-C₁₀ alkyl radical; more preferably R¹⁴ is a hydrogen atom;-   R¹¹ and R¹², equal to or different from each other are hydrogen    atoms or C₁-C₁₀ hydrocarbon radicals optionally containing    heteroatoms belonging to groups 13-17 of the Periodic Table of the    Elements; preferably R¹¹ and R¹² are hydrogen atoms or C₁-C₁₀ alkyl    radicals; more preferably R¹¹ is a hydrogen atom and; R¹² is a    hydrogen atom or a C₁-C₁₀ alkyl radical such as methyl, ethyl    isopropyl or terbutyl radical.

More preferably the compound of formula (Ia) has formula (Ib)

Wherein

-   M, X, R¹, R^(1a), R⁷ and R¹² have been described above; R¹³, equal    to or different from each other, is hydrogen atom, or a C₁-C₁₀    hydrocarbon radical; preferably R₁₃ is hydrogen atom or a C₁-C₅    alkyl radical; more preferably R₁₃ is hydrogen atom.

Alumoxanes used as component b) or c) in the above processes can beobtained by reacting water with an organo-aluminium compound of formulaH_(j)AlU_(3-j) or H_(j)Al₂U_(6-j), where the U substituents, same ordifferent, are hydrogen atoms, halogen atoms, C₁-C₂₀-alkyl,C₃-C₂₀-cycloalkyl, C₆-C₂₀-aryl, C₇-C₂₀-alkylaryl or C₇-C₂₀-arylalkylradicals, optionally containing silicon or germanium atoms, with theproviso that at least one U is different from halogen, and j ranges from0 to 1, being also a non-integer number. In this reaction the molarratio of Al/water is preferably comprised between 1:1 and 100:1.

The alumoxanes used in the process according to the invention areconsidered to be linear, branched or cyclic compounds containing atleast one group of the type:

wherein the substituents U, same or different, are defined above.

In particular, alumoxanes of the formula:

can be used in the case of linear compounds, wherein n¹ is 0 or aninteger from 1 to 40 and the substituents U are defined as above; oralumoxanes of the formula:

can be used in the case of cyclic compounds, wherein n2 is an integerfrom 2 to 40 and the U substituents are defined as above.

Examples of alumoxanes suitable for use according to the presentinvention are methylalumoxane (MAO), tetra-(isobutyl)alumoxane (TIBAO),tetra-(2,4,4-trimethyl-pentyl)alumoxane (TIOAO),tetra-(2,3-dimethylbutyl)alumoxane (TDMBAO) andtetra-(2,3,3-trimethylbutyl)alumoxane (TTMBAO).

Particularly interesting cocatalysts are those described in WO 99/21899and in WO01/21674 in which the alkyl and aryl groups have specificbranched patterns.

Non-limiting examples of aluminium compounds that can be reacted withwater to give suitable alumoxanes (b), described in WO 99/21899 andWO01/21674, are:

-   tris(2,3,3 trimethyl-butyl)aluminium, tris(2,3    dimethyl-hexyl)aluminium, tris(2,3 dimethyl-butyl)aluminium,    tris(2,3 dimethyl-pentyl)aluminium, tris(2,3    dimethyl-heptyl)aluminium, tris(2 methyl-3-ethyl-pentyl)aluminium,    tris(2 methyl-3-ethyl-hexyl)aluminium, tris(2    methyl-3-ethyl-heptyl)aluminium, tris(2    methyl-3-propyl-hexyl)aluminium, tris(2    ethyl-3-methyl-butyl)aluminium, tris(2    ethyl-3-methyl-pentyl)aluminium, tris(2,3 diethyl-pentyl)aluminium,    tris(2 propyl-3-methyl-butyl)aluminium, tris(2    isopropyl-3-methyl-butyl)aluminium, tris(2    isobutyl-3-methyl-pentyl)aluminium, tris(2,3,3    trimethyl-pentyl)aluminium, tris(2,3,3 trimethyl-hexyl)aluminium,    tris(2 ethyl-3,3-dimethyl-butyl)aluminium, tris(2    ethyl-3,3-dimethyl-pentyl)aluminium, tris(2    isopropyl-3,3-dimethyl-butyl)aluminium, tris(2    trimethylsilyl-propyl)aluminium, tris(2    methyl-3-phenyl-butyl)aluminium, tris(2    ethyl-3-phenyl-butyl)aluminium, tris(2,3    dimethyl-3-phenyl-butyl)aluminium, tris(2-phenyl-propyl)aluminium,    tris[2-(4-fluoro-phenyl)-propyl]aluminium,    tris[2-(4-chloro-phenyl)-propyl]aluminium,    tris[2-(3-isopropyl-phenyl)-propyl]aluminium,    tris(2-phenyl-butyl)aluminium, tris(3 methyl-2-phenyl-butyl)    aluminium, tris(2-phenyl-pentyl)aluminium,    tris[2-(pentafluorophenyl)-propyl]aluminium,    tris[2,2-diphenyl-ethyl]aluminium and    tris[2-phenyl-2-methyl-propyl]aluminium, as well as the    corresponding compounds wherein one of the hydrocarbyl groups is    replaced with a hydrogen atom, and those wherein one or two of the    hydrocarbyl groups are replaced with an isobutyl group.

Amongst the above aluminium compounds, trimethylaluminium (TMA),triisobutylaluminium (TIBA), tris(2,4,4-trimethyl-pentyl)aluminium(TIOA), tris(2,3-dimethylbutyl)aluminium (TDMBA) andtris(2,3,3-trimethylbutyl)aluminium (TTMBA) are preferred.

Non-limiting examples of compounds able to form an alkylmetallocenecation are compounds of formula D+E−, wherein D+ is a Brønsted acid,able to donate a proton and to react irreversibly with a substituent Xof the metallocene of formula (I) and E− is a compatible anion, which isable to stabilize the active catalytic species originating from thereaction of the two compounds, and which is sufficiently labile to beremoved by an olefinic monomer. Preferably, the anion E− comprises oneor more boron atoms. More preferably, the anion E− is an anion of theformula BAr4(−), wherein the substituents Ar which can be identical ordifferent are aryl radicals such as phenyl, pentafluorophenyl orbis(trifluoromethyl)phenyl. Tetrakis-pentafluorophenyl borate isparticularly preferred compound, as described in WO 91/02012. Moreover,compounds of formula BAr3 can be conveniently used. Compounds of thistype are described, for example, in the International patent applicationWO 92/00333. Other examples of compounds able to form analkylmetallocene cation are compounds of formula BAr3P wherein P is asubstituted or unsubstituted pyrrol radical. These compounds aredescribed in WO01/62764. Compounds containing boron atoms can beconveniently supported according to the description of DE-A-19962814 andDE-A-19962910. All these compounds containing boron atoms can be used ina molar ratio between boron and the metal of the metallocene comprisedbetween about 1:1 and about 10:1; preferably 1:1 and 2.1; morepreferably about 1:1.

Non limiting examples of compounds of formula D+E− are:

-   Tributylammoniumtetra(pentafluorophenyl)aluminate,-   Tributylammoniumtetra(trifluoromethylphenyl)borate,-   Tributylammoniumtetra(4 fluorophenyl)borate,-   N,N-Dimethylbenzylammonium-tetrakispentafluorophenylborate,-   N,N-Dimethylhexylamonium-tetrakispentafluorophenylborate,-   N,N Dimethylaniliniumtetrakis(pentafluorophenyl)borate,-   N,N Dimethylaniliniumtetrakis(pentafluorophenyl)aluminate,-   N,N-Dimethylbenzylammonium-tetrakispentafluorophenylborate,-   N,N-Dimethylhexylamonium-tetrakispentafluorophenylborate,-   Di(propyl)ammoniumtetrakis(pentafluorophenyl)borate,-   Di(cyclohexyl)ammoniumtetrakis(pentafluorophenyl)borate,-   Triphenylcarbeniumtetrakis(pentafluorophenyl)borate,-   Triphenylcarbeniumtetrakis(pentafluorophenyl)aluminate,-   Ferroceniumtetrakis(pentafluorophenyl)borate,-   Ferroceniumtetrakis(pentafluorophenyl)aluminate.-   Triphenylcarbeniumtetrakis(pentafluorophenyl)borate, and-   N,N Dimethylaniliniumtetrakis(pentafluorophenyl)borate.

Preferably the composition obtainable with the process of the presentcomprises:

-   a) from 30 wt % to 50 wt % of a propylene homopolymer or a    propylene-ethylene copolymer containing from 0.1 wt % to 5 wt % of    ethylene derived units;-   b) from 40 wt % to 65 wt % of a copolymer of ethylene and at least    one C₃-C₂₀ alpha olefins, wherein the ethylene derived units content    ranges from 15 wt % to 70 wt %; preferably from 20 wt % to 65 wt %;-   c) from 3 wt % to 7 wt % of polyethylene homopolymer or an ethylene    and at least one C₃-C₂₀ alpha olefins copolymer containing from 99.9    wt % to 95.0 wt % of ethylene wherein the at least one C₃-C₂₀ alpha    olefins comonomer is the same used in component b);-   the sum a)+b)+c) being 100;

Examples of C₃-C₂₀ alpha olefins are propylene, 1-butene, 1-hexene,1-ottene; preferred monomer is propylene.

The catalysts system to be used in the process of the present inventioncan be supported on an inert carrier. This is achieved by depositingmetal complex A) and the iron complex B) or the product of the reactionthereof with the component C), or the component C) and then metalcomplex A) and the iron complex B) on an inert support. The support canbe a porous solid such as talc, a sheet silicate, an inorganic oxide ora finely divided polymer powder (e.g. polyolefin). Suitable inorganicoxides may be found among the oxides of elements of groups 2, 3, 4, 5,13, 14, 15 and 16 of the Periodic Table of the Elements. Examples ofoxides preferred as supports include silicon dioxide, aluminum oxide,and also mixed oxides of the elements calcium, aluminum, silicon,magnesium or titanium and also corresponding oxide mixtures, magnesiumhalides, styrene/divinylbenzene copolymers, polyethylene orpolypropylene. Other inorganic oxides which can be used alone or incombination with the abovementioned preferred oxidic supports are, forexample, MgO, ZrO2, TiO2 or B2O3.

A suitable class of supports which can be used is that constituted byporous organic supports functionalized with groups having activehydrogen atoms. Particularly suitable are those in which the organicsupport is a partially crosslinked styrene polymer. Supports of thistype are described in European application EP-633 272.

Another class of inert supports particularly suitable for use accordingto the invention is that of polyolefin porous prepolymers, particularlypolyethylene.

The support materials used preferably have a specific surface area inthe range from 10 to 1000 m2/g, a pore volume in the range from 0.1 to 5ml/g and a mean particle size of from 1 to 500 m. Preference is given tosupports having a specific surface area in the range from 50 to 500m2/g, a pore volume in the range from 0.5 to 3.5 ml/g and a meanparticle size in the range from 5 to 350 m. Particular preference isgiven to supports having a specific surface area in the range from 200to 400 m2/g, a pore volume in the range from 0.8 to 3.0 ml/g and a meanparticle size of from 10 to 300 μm.

The inorganic support can be subjected to a thermal treatment, e.g. toremove adsorbed water. Such a drying treatment is generally carried outat from 80 to 300° C., preferably from 100 to 200° C., with drying atfrom 100 to 200° C. preferably being carried out under reduced pressureand/or a blanket of inert gas (e.g. nitrogen), or the inorganic supportcan be calcined at from 200 to 1 000° C. to produce the desiredstructure of the solid and/or set the desired OH concentration on thesurface. The support can also be treated chemically using customarydesiccants such as metal alkyls, preferably aluminum alkyls,chlorosilanes or SiCl4, or else methylaluminoxane.

Appropriate treatment methods are described, for example, in WO00/31090. The inorganic support material can also be chemicallymodified. For example, treatment of silica gel with (NH4)2SiF6 leads tofluorination of the silica gel surface, or treatment of silica gels withsilanes containing nitrogen-, fluorine- or sulfur-containing groupsleads to correspondingly modified silica gel surfaces.

Organic support materials such as finely divided polyolefin powders(e.g. polyethylene, polypropylene or polystyrene) can also be used andare preferably likewise freed of adhering moisture, solvent residues orother impurities by means of appropriate purification and dryingoperations before use. It is also possible to use functionalized polymersupports, e.g. supports based on polystyrene, via whose functionalgroups, for example ammonium or hydroxy groups, at least one of thecatalyst components can be immobilized. The solid compound obtained bysupporting the catalyst system object of the present invention on acarrier in combination with the further addition of the alkylaluminiumcompound either as such or prereacted with water if necessary, can beusefully.

Preferred support is silica.

With the catalyst of the present invention it is possible to obtain athree components composition with a two steps polymerization process,furthermore due to the presence of the component c) that act ascompatibilizer it is also possible to obtain a composition that isricher in component b) (the rubber) as reactor without being sticky.Mainly, component c) is produced in the second polymerization step.Furthermore the presence of component c) enhances the compatibilitybetween component a) and b) so that to have a final composition having abetter homogeneity. The composition obtained with the process of thepresent invention can be used in extrusion processes for obtainingextruded articles such as films, pipes, fibers, sheets, profiles and thelike, in injection molding processes such as injection molding, blowmolding, rotomolding and the like for obtaining molded articles such asfor example, automotive parts, bumpers, cases for battery, containersand the like or it can be used in thermoformed processes for obtainingthermoformed articles.

EXAMPLES

The following examples are given to illustrate the present inventionwithout limiting purpose.

Crystaf Analysis

Crystallization Analysis Fractionation (CRYSTAF) technique involvesdissolving a sample in a solvent at high temperature, then cooling thesolution slowly to cause fractionation of the sample based onsolubility. For semi-crystalline samples, including blends, solubilitydepends primarily on crystallizability: portions of the sample that aremore crystalline will precipitate out of solution at a highertemperature than portions of the sample that are less crystalline.

The relative amount of sample in solution as a function of temperatureis measured using an infrared (IR) detector to obtain the cumulativesolubility distribution. The soluble fraction (SF) is defined as the IRsignal at the lowest temperature (at 0° C.) divided by the IR signalwhen all the sample is dissolved at high temperature, and corresponds tothe weight fraction of sample that has not crystallized.

A commercial CRYSTAF 200 instrument (Polymer Char S. A., Valencia,Spain) with five stirred stainless steel vessels of 60 mL volume wasused to perform this test. The technique is outlined in Harald Pasch*,Robert Brüll², Udo Wahner², Benjamin Monrabal³ MACROMOL. MATER. ENG.279, 46-51 (2000).

In contrast to the procedure in the literature given approximately 15 mgof sample were dissolved for 60 min at 160° C. in 30 mL of1,2-dichlorobenzene. The solution was then stabilized for 90 min at 95°C.

The crystallization was carried out from 95 to 30° C. at acrystallization rate of 0.1° C./min. A dual wavelength infrared detectorwith a heated flow through cell maintained at 150° C. was used tomeasure the polymer concentration in solution at regular intervalsduring the crystallization cycle; the measuring wavelength was 3.5 μmand the reference wavelength was 3.6 μm. The cumulative solubleconcentration is measured as the polymer crystallizes while thetemperature is decreased.

The CRYSTAF peak temperature and area are identified by the peakanalysis module included in the CRYSTAF Software (Version 200 Lb^PolymerChar, Valencia, Spain). The CRYSTAF peak finding routineidentifies a peak temperature as a maximum in the dW/dT and the areabetween the largest positive inflections on either side of theidentified peak in the derivative curve.

Polyethylene Homopolymer (HDPE) Content (Component c)

The HDPE content has been measured by subjecting each fraction to theCrystaf® analysis, the fraction detected at a temperature higher than80° C. was considered as HDPE.

Propylene Homopolymer Content (Component a)

The propylene homopolymer content has been measured by subjecting eachfraction to the Crystaf® analysis, the fraction detected at atemperature comprised between 60° C. and 80° C. was considered aspropylene homopolymer.

MFR

The Melt Flow Rate was determined at 190° C. under a load of 21.6 kg(190° C./21.6 kg) in accordance with ISO 1133.

GPC

The determination of the molar mass distributions and the means Mn, Mw,M_(z) and Mw/Mn derived therefrom was carried out by means ofhigh-temperature gel permeation chromatography on a WATERS 150 C using amethod based on DIN 55672 and the following columns connected in series:3× SHODEX AT 806 MS, 1× SHODEX UT 807 and 1× SHODEX AT-G under thefollowing conditions: solvent: 1,2,4-trichlorobenzene (stabilized with0.025% by weight of 2,6-di-tert-butyl-4-methylphenol), flow: 1 ml/min,500 ml injection volume, temperature: 140° C. The columns werecalibrated with polyethylene standards with molar masses of from 100 bis10⁷ g/mol. The evaluation was carried out by using the Win-GPC softwareof Fa. HS-Entwicklungsgesellschaft für wissenschaftliche Hard- undSoftware mbH, Ober-Hilbersheim.

Xylene Soluble and Insoluble Fractions

2.5 g of polymer and 250 cm³ of xylene are introduced in a glass flaskequipped with a refrigerator and a magnetical stirrer. The temperatureis raised in 30 minutes up to the boiling point of the solvent. The soobtained clear solution is then kept under reflux and stirring forfurther 30 minutes. The closed flask is then kept for 30 minutes in abath of ice and water and in thermostatic water bath at 25° C. for 30minutes as well. The so formed solid is filtered on quick filteringpaper. 100 cm³ of the filtered liquid is poured in a previously weighedaluminum container which is heated on a heating plate under nitrogenflow, to remove the solvent by evaporation. The container is then keptin an oven at 80° C. under vacuum until constant weight is obtained. Theweight percentage of polymer soluble in xylene at room temperature isthen calculated.

Preparation of the Mixed Catalyst Systems:

Component i) isMe₂Si(2-Me-4-Ph-tetrahydro-s-indacenyl)(2-iPr-4-(4-tBuPh)-Ind)ZrMe₂) wasprepared according to the description of preparation of metallocene 2 ofWO 2005/058916.

Component ii) 2 is2,6-Bis[1-(2-Chlor-2,4,6-trimethylphenylimino)ethyl]pyridine iron(II)dichloride. It was prepared as in example 1 of WO 98/27124 and reactedin an analogous manner with iron(II) chloride to said complex 2.

Methylalumoxane (MAO) was received from Chemtura Inc. as a 30% (w/w)toluene solution.

Support:

-   XPO-2326A, a spray-dried silica gel from Grace-   Support pretreatment XPO-2326 A was calcinated at 600° C. for 6    hours.    Preparation of the Catalyst System:

361.2 mg of complex 1 and 26.1 mg of complex 2 and 3,4 ml of toluenewere placed in a 50 ml flask. 11.4 ml of MAO (30% in toluene) was addedto this mixture. The solution was stirred for 20 min at ambienttemperature. A 250 ml flask was loaded with 9.2 g of calcinatedXPO-2326A and cooled to 0° C. The red colored complex/MAO solution wassuccessively added at vigorous stirring within 5 min. The powder wascontinuously stirred for 1 hour. 60 ml of heptane were added to thestrawberry red powder, resulting a slurry, which was transferred into aglass frit. The solvent was filtered of and the solid dried in acontinues Ar stream until a free flowing powder was obtained. 17.3 g ofstrawberry red powder having 28.9% of volatiles was obtained. The ratioof loadings of compound i) and that of compound ii) is E μmol/g:μmol/gand the Al/(compound i)+compound ii)) ratio is F:1 mol:mol as reportedon table 1.

E F compl1:compl2 Al:Zr + Fe Catalyst μmol/g:μmol/g (mol:mol) 1 55/5 98Polymerization:

A 10 l batch autoclave was pressurized and vented one time with drynitrogen and 3 times with propylene up to a pressure of 5 bar-g. Afterthe autoclave being conditioned, 30 ml of TiBA (triisobutylaluminum)(50%solution in Toluene), hydrogen as indicated in table 2 and 500 g ofliquid propylene were introduced at 30° C. 136 mg of neat catalystprepared as described above were flushed into the reactor using another1000 g of liquid propylene. The reactor temperature was raised to 65° C.and kept constant for a time indicated in table 2. After that thepressure was decreased to 0.3 bar-g by venting off all volatiles. Thereactor was pressurized with 5 bar-g of nitrogen and vented again. Inthe following step a gas mixture of propylene and of ethylene in table 2was introduced until a pressure of 21 bar-g was reached. The pressurewas kept constant by feeding the said gas mixture for a time indicatedin table 2. After that all volatiles were released and the autoclave waspressurized and vented 3 times with dry nitrogen. 1270 g of polymer, afree flowing powder, were discharged from the autoclave through itsbottom discharge valve. Resulting a yield of 9.4 kg/gh. Thepolymerization conditions are indicated in table 2 and thecharacteristics of the polymer obtained are indicated in table 3.

TABLE 2 4.6-104 4.6-076 4.6-077 4.6-078 4.6-079 4.6-085 Ex Ref* 1 2 3 45 Gas phase composition C2 Mol % 60 70 60 50 40 20 C3 Mol % 40 30 40 5060 80 Step a Min 22 15 15 15 15 15 Step b min 67 45 45 45 45 45Polymerization Kgpol/g 3.7 9.4 6.0 6.0 6.6 6.2 activity catxh C2ethylene, C3 propylene, H2 hydrogen *the reference example was carriedout with a catalyst system prepared as above described but withoutcomponent ii)

TABLE 3 4.6-104 4.6-076 4.6-077 4.6-078 4.6-079 4.6-085 Ex Ref* 1 2 3 45 MFR g/10′ <0.1 0.9 0.5 0.1 4.8 <0.1 IV dl/g 3.1 2.5 2.8 3.2 2.6 3.8 PEwt % 0 2.8 4.1 5.2 3.6 3.2 PP wt % 24 32 36 28 29 25 Rubber * wt % 7665.2 59.9 66.8 67.4 71.8 C2 rubber wt % 32 21 26 36 47 63 XS Wt % 70 5951 56 50 60 Mw/Mn 2.2 17.9 8.0 8.1 20.0 3.1 Mw 418062 334756 338581384364 328737 525001 PP polypropylene (component a) PE polyethylene(component b) Rubber ethylene copolymer (component c) XS solubles inxylene at 25° C. * the percentage of rubber is calculated from thepercentage of PP and PE

What is claimed is:
 1. A process for obtaining a polyolefin compositioncomprising: A) contacting in a first polymerization step comprising apressurized reactor propylene and optionally ethylene optionally in gasphase and a catalyst system to obtain an overall content of a firstcomponent (a) ranging from 25-70 wt %, based on the total wt % of thepolyolefin composition, wherein the first component (a) is a propylenehomopolymer, or a propylene-ethylene copolymer comprising 0.1-10 wt % ofethylene; B) further contacting in a second polymerization stepcomprising the pressurized reactor of step A) ethylene and at least oneC₃-C₂₀ alpha olefin optionally in gas phase and the catalyst system toobtain an overall content of a second component (b) ranging from 27-70wt %, based on the total wt % of the polyolefin composition, wherein thesecond component (b) is an ethylene copolymer comprising 15-70 wt %ethylene and at least one C₃-C₂₀ alpha-olefin, and an overall content ofa third component (c) ranging from 3-20 wt %, based on the total wt % ofthe polyolefin composition, wherein the third component (c) ispolyethylene homopolymer or copolymer comprising 95-99.9 wt % ethyleneand at least one C₃-C₂₀ alpha-olefin, wherein the at least one C₃-C₂₀alpha-olefin comonomer is the same used in component b) to form apolyolefin composition; and C) discharging the polyolefin composition:wherein the catalyst system comprises: i) a metallocene compound of thegeneral formula (I):

wherein M is selected from the group consisting of titanium, zirconiumand hafnium; X, whether the same or different, is selected from thegroup consisting of hydrogen, a halide, an —R, —OR, —SO₃CF₃, —CO₂R, —SR,—NR₂ and —PR₂ group, wherein R is selected from the group consisting ofa linear or branched, cyclic or acyclic, C₁-C₄₀ alkyl, C₂-C₄₀ alkenyl,C₂-C₄₀ alkynyl, C₆-C₄₀ alkylaryl and C₇-C₄₀ alkylaryl and C₇-C₄₀arylalkyl radicals; optionally comprising heteroatoms from Groups 13-17of the Periodic Table of Elements; R¹, R², R³, R⁴, R⁵, R⁶ and R⁷, equalto or different from each other, are selected from the group consistingof hydrogen and C₁-C₄₀ hydrocarbon radicals optionally comprisingheteroatoms from Groups 13-17 of the Periodic Table of Elements; or twoor more groups between R¹, R², R³, R⁴, R⁵ and R⁶ can be fused to form asaturated or unsaturated, 5- or 6-membered rings and optionally compriseC₁-C₂₀ alkyl radical substituents; ii) at least one iron complex of thegeneral formula (II):

wherein the radical X¹ is selected from the group consisting ofhydrogen, a halide, —R, —OR, —SO₃CF₃, —CO₂, —SR, —NR₂ and —PR2 groups,wherein R is selected from a linear, branched, saturated and/orunsaturated C₁-C₂₀ alkyl, C₃-C₂₀ cycloalkyl, C₆-C₂₀ aryl, C₇-C₂₀alkylaryl and C7-C20 arylalkyl radical, optionally containingheteroatoms from Groups 13-17 of the Periodic Table of Elements; or X¹can optionally form a substituted or unsubstituted butadienyl radical oran OR′O group, wherein R′ is a divalent radical selected from C₁-C₂₀alkylidene, C₆-C₄₀ arylidene, C₇-C₄₀ alkylarylidene and C₇-C₄₀arylalkylidene radicals; D is an uncharged donor; s is 1, 2, 3 or 4, tranges from 0 to 4; R⁸, equal to or different from each other, areselected from the group consisting of hydrogen and C₁-C₄₀ hydrocarbonradicals optionally containing heteroatoms belonging to Groups 13-17 ofthe Periodic Table of Elements; R¹⁰, equal to or different from eachother, are selected from the group consisting of hydrogen and C₁-C₄₀hydrocarbon radicals optionally containing heteroatoms belonging toGroups 13-17 of the Periodic Table of Elements; R9, equal to ordifferent from each other, are selected from the group consisting ofhydrogen and C₁-C₄₀ hydrocarbon radicals optionally containingheteroatoms belonging to Groups 13-17 of the Periodic Table of Elements;and iii) an alumoxane or a compound capable of forming an alkyl cationwith complexes of formula (I) and (II).
 2. The polymerization process ofclaim 1, wherein the compound of formula (I) has the general formula(Ia):

wherein M, X, R¹, R², R⁴, R⁵, R⁶ and R⁷ are defined in claim 1 andR^(1a) has the general formula (III):

wherein the symbol * marks the bound with the cyclopentadienyl moiety;R13,equal to or different from each other, is a C₁-C₁₅ hydrocarbonradical optionally containing heteroatoms belonging to Groups 13-17 ofthe Periodic Table of Elements; R¹⁴ is selected from the groupconsisting of hydrogen and a C₁-C₁₅ hydrocarbon radical optionallycontaining heteroatoms belonging to Groups 13-17 of the Periodic Tableof Elements; and R¹¹ and R12, equal to or different from each other, areselected from the group consisting of hydrogen and C₁-C₁₀ hydrocarbonradicals optionally containing heteroatoms belonging to Groups 13-17 ofthe Periodic Table of Elements.
 3. The polymerization process of claim1, wherein the compound of formula (I) has the general formula (Ib):

wherein M, X, R¹, R^(1a), R⁷ and R¹² are defined in claims 1 and 2, andR¹³, equal to or different from each other, is selected from the groupconsisting of hydrogen and a C₁-C₁₀ hydrocarbon radical.
 4. Thepolymerization process of claim 1, wherein the catalyst system issupported on an inert carrier.
 5. The polymerization process of claim 1,wherein the molar ratio of the metallocene compound of formula (I) andthe iron complex of formula (II) ranges from 3:1 to 50:1.
 6. Thepolymerization process of claim 1, wherein the polyolefin compositioncomprises: a) 30-50 wt % of a propylene homopolymer; b) 40-65 wt % of anethylene/propylene copolymer, wherein the ethylene content ranges from20-65 wt %; and c) 3-7 wt % of a polyethylene homopolymer; wherein thesum of a)+b)+c) is 100 wt %.
 7. The polymerization process of claim 6,wherein the polyolefin composition comprises a polyolefin blend.
 8. Thepolymerization process of claim 6, wherein the polyolefin compositioncomprises an extruded article.
 9. The polymerization process of claim 8,wherein the extruded article is selected from the group consisting of afilm, a pipe, a fiber and a sheet.
 10. The polymerization process ofclaim 6, wherein the polyolefin composition comprises a molded article.11. The polymerization process of claim 6, wherein the polyolefincomposition comprises a thermoformed article.
 12. The polymerizationprocess of claim 10, wherein the molded article is selected from thegroup consisting of an automotive part, a bumper, a battery case and acontainer.